Ground clamp



FIG. 1 is a perspective view of a ground clamp showing our new design.

FIG. 2 is a front elevational plan view thereof;

FIG. 3 is a top plan view thereof;

FIG. 4 is a bottom plan view thereof;

FIG. 5 is a right elevational view thereof; 

The ornamental design for a ground clamp, substantially as shown and described. 